Three professors think there is a good way for people to start going back to work and school. Their suggestion is partly based on how long people who get the virus usually become contagious, which is three days on average.

First, the population would be divided into two groups — like our cars were divided into two groups by odd and even license plates when OPEC made trouble in the 1970s and it was very hard to buy gas.

Grouping could be done using the first letter of everyone’s last name, such as A to L and M to Z. Doing the groups that way would give the members of a family the same schedule (of course, there would have to be flexibility to handle special cases).

Each group would then go to work or school on a schedule of four days on, ten days off. Group A to L would start work on a Monday, work four days, then take off ten days. Group M to Z would go to work or school the following Monday, work four days and then take off.

The result would be that people would be at work or school 40% of the time: four days instead of the usual ten every two-weeks (of course, there would have to be flexibility again, one reason being that somebody has to mind the store or the police station on Fridays and weekends).

Working or being educated would still be possible during our ten days “off” at home. The totally unemployed would be working part-time. The point is that we’d be taking a step toward a more normal existence for most people.

When I read the professors’ article, I wondered why they chose a four-day schedule if people are usually contagious after three days. Aside from how four days fits nicely into the fourteen days of two weeks, they believe that getting sick would be unlikely even if people were in close contact and someone became contagious at the beginning of the four days. They did some math:

Models we created at the Weizmann Institute in Israel predict that this two-week cycle can reduce the virus’s reproduction number — the average number of people infected by each infected person — below one. So a 10-4 cycle could suppress the epidemic while allowing sustainable economic activity.

More from the article:

Even if someone is infected, and without symptoms, he or she would be in contact with people outside their household for only four days every two weeks, not 10 days, as with a normal schedule. This strategy packs another punch: It reduces the density of people at work and school, thus curtailing the transmission of the virus.

The cyclic strategy is easy to explain and to enforce. It is equitable in terms of who gets to go back to work. It applies at any scale: a school, a firm, a town, a state. A region that uses the cyclic strategy is protected: Infections coming from the outside cannot spread widely if the reproduction number is less than one. It is also compatible with all other countermeasures being developed.

Workers can, and should still, use masks and distancing while at work. This proposal is not predicated, however, on large-scale testing, which is not yet available everywhere in the United States and may never be available in large parts of the world. It can be started as soon as a steady decline of cases indicates that lockdown has been effective.

The cyclic strategy should be part of a comprehensive exit strategy, including self-quarantine by those with symptoms, contact tracing and isolation, and protection of risk groups. The cyclic strategy can be tested in limited regions for specific trial periods, even a month. If infections rates grow, it can be adjusted to fewer work days. Conversely, if things are going well, additional work days can be added. In certain scenarios, only four or five lockdown days in each two-week cycle could still prevent resurgence.

The coronavirus epidemic is a formidable foe, but it is not unbeatable. By scheduling our activities intelligently, in a way that accounts for the virus’s intrinsic dynamics, we can defeat it more rapidly, and accelerate a full return to work, school and other activities.